The present invention relates to technology for acquiring a backup in a storage system, which is the transfer destination of a journal used for remote copying.
Technology related to remote copying from a primary storage system to a secondary storage system is known. As one method of remote copying, there is a method that uses a journal, which is information related to the update history of a primary logical volume (hereinafter, PVOL). More specifically, for example, when data is written to a PVOL, a primary storage system prepares a journal comprising this data, and transfers this journal to a secondary storage system. The secondary storage system writes the data inside this journal to a secondary logical volume (hereinafter, SVOL).
In a secondary storage system, it can be desirable to acquire a data backup at a specified time status. For example, the technology disclosed in Japanese Patent Laid-open No. 2006-155676 (hereinafter, Literature 1) is related to acquiring a data backup at a specified time status.
Further, for example, the technology disclosed in Japanese Patent Laid-open No. 2005-18738 (hereinafter, Literature 2) is related to restoring data at an arbitrary point in time using a journal.
It is supposed that there are one or more secondary storage systems having a plurality of SVOLs, which constitute a plurality of volume pairs respectively with a plurality of PVOLs that exist in one or more primary storage systems, and that a data backup is acquired at a specified time for each volume pair in these one or more secondary storage systems.
In this case, in Literature 1, if the acquisition of a backup fails in at least one of the volume pairs, a backup is acquired for the other volume pair. Thus, consistency cannot be maintained for a plurality of backups in one or more secondary storage systems.
According to the technology disclosed in Literature 2, it is possible to restore data at a specified time by sequentially writing the data in a plurality of journals, which were prepared from a certain point in time until a specified time relative to a snapshot of the certain point in time, to this snapshot. However, there is the risk that the more numerous the number of journals from a certain point in time until a specified time, the longer it will take for restoration.